package Lee_code;

import java.util.HashSet;

public class Lee_70 {

    public int climbStairs(int n) {
        int[] dp = new int[n+1];
        dp[1] = 1;
        dp[2] = 2;
        for(int i=3; i<=n; i++)
        {
            dp[n] = dp[n-1] + dp[n-2];
        }
        return dp[n];
    }

}
